GEMS (Girls health Enrichment Multi-site studies) is a unique clinical trial in which different weight gain prevention interventions are being tested in two Field Centers (FCs) for high risk, preadolescent African American girls. While the interventions differ between the two FCs, there are common measures and a collaborative data base. Phase I activities are now complete, with two of the four initially funded FCs progressing to Phase II. We propose the following specific aims for the Memphis Field Center: (1) To conduct a full-scale 2-year, randomized controlled clinical trial for weight gain prevention among high risk, preadolescent African American girls; (2) To recruit 300 African American girls and their parents/caregivers, deliver a 2-year intervention, perform common and site-specific measurements, and contribute to the collaborative database shared by Memphis and Stanford; (3) To evaluate the efficacy of the intervention on our primary endpoint body mass index (BMI) and on the secondary endpoints of dietary intake, physical activity, and psychosocial variables. Additionally, the Memphis site will evaluate the efficacy of the intervention on the site-specific endpoints of percent body fat measured by dual energy x-ray absorptiometry (DEXA) and bioelectric impedance (BIA); (4) To conduct exploratory and process evaluation analyses to identify variables that mediate outcomes; and (5) To collaborate with Stanford to perform joint analyses of the collaborative data base to address questions which neither FC could address alone.